RESUMEN
Mucopolysaccharidoses (MPSs) are a group of genetic alterations whose effect is the progressive intralysosomal accumulation of glycosaminoglycans. Affected individuals are deficient in one or more lysosomal enzymes which, depending on the MPS, may cause coarse facial features, short stature, multiple skeletal dysplasia, joint stiffness, or developmental delay. Their diagnosis is mostly performed late or incorrectly, and it represents a challenge since it requires specialized tests only performed in major cities. This makes it difficult for patients to have access to physicians since their geographical location is distant and therefore, the use of samples collected in solid-phase represents an advantage for the study of high-risk populations. In addition, epidemiological information about rare diseases, especially in Latin America, is scarce or inconsistent. Our aim was to report the experience of 20 years of selective screening by assessing enzyme activity and reporting incidence values of MPS in Colombia. This study validated a group of fluorometric endpoint techniques in 8239 patients. The samples were dried blood spots (DBS) collected on filter paper and leukocyte extracts. Reference values in the Colombian population for α-l-iduronidase, iduronate 2-sulfatase, α-N-acetylglucosaminidase, N-acetylglucosamine-6-sulfate sulfatase, ß-galactosidase, arylsulfatase B, and ß-glucuronidase were established in leukocyte extracts, and patients reference ranges were updated in the case of DBS samples. Incidence values were calculated for each MPS and the distribution of cases across the country is also shown. This study offers very useful information for the health system, the scientific community, and it facilitates the diagnosis of these disorders. This is indispensable when seeking to develop new diagnostic or treatment approaches for patients.
RESUMEN
Enzyme replacement therapy (ERT) improves somatic manifestations in mucopolysaccharidoses (MPS). However, because intravenously administered enzymes cannot cross the blood-brain barrier (BBB), ERT is ineffective against the progressive neurodegeneration and resultant severe central nervous system (CNS) symptoms observed in patients with neuronopathic MPS. Attempts to surmount this problem have been made with intrathecal and intracerebroventricular ERT in order to achieve CNS effects, but the burdens on patients are inimical to long-term administrations. However, since pabinafusp alfa, a human iduronate-2-sulfatase fused with a BBB-crossing anti-transferrin receptor antibody, showed both central and peripheral efficacy in a mouse model, subsequent clinical trials in a total of 62 patients with MPS-II (Hunter syndrome) in Japan and Brazil substantiated this dual efficacy and provided an acceptable safety profile. To date, pabinafusp alfa is the only approved intravenous ERT that is effective against both the somatic and CNS symptoms of patients with MPS-II. This article summarizes the previously obtained preclinical and clinical evidence related to the use of this drug, presents latest data, and discusses the preclinical, translational, and clinical challenges of evaluating, ameliorating, and preventing neurodegeneration in patients with MPS-II.
Asunto(s)
Terapia de Reemplazo Enzimático , Iduronato Sulfatasa/uso terapéutico , Mucopolisacaridosis II/tratamiento farmacológico , Animales , Biomarcadores/líquido cefalorraquídeo , Barrera Hematoencefálica/efectos de los fármacos , Barrera Hematoencefálica/metabolismo , Encéfalo/metabolismo , Ensayos Clínicos como Asunto , Modelos Animales de Enfermedad , Evaluación Preclínica de Medicamentos , Humanos , Iduronato Sulfatasa/genética , Iduronato Sulfatasa/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Mucopolisacaridosis II/patología , Proteínas Recombinantes/efectos adversos , Proteínas Recombinantes/farmacología , Proteínas Recombinantes/uso terapéutico , Índice de Severidad de la EnfermedadRESUMEN
Mucopolysaccharidosis type II (MPS II) is an X-linked inherited disease caused by pathogenic variants in the IDS gene, leading to deficiency of the lysosomal enzyme iduronate-2-sulfatase and consequent widespread storage of glycosaminoglycans, leading to several clinical consequences, with progressive manifestations which most times includes cognitive decline. MPS II has wide allelic and clinical heterogeneity and a complex genotype-phenotype correlation. We evaluated data from 501 Brazilian patients diagnosed with MPS II from 1982 to 2020. We genotyped 280 of these patients (55.9%), which were assigned to 206 different families. Point mutations were present in 70% of our patients, being missense variants the most frequent. We correlated the IDS pathogenic variants identified with the phenotype (neuronophatic or non-neuronopathic). Except for two half-brothers, there was no discordance in the genotype-phenotype correlation among family members, nor among MPS II patients from different families with the same single base-pair substitution variant. Mothers were carriers in 82.0% of the cases. This comprehensive study of the molecular profile of the MPS II cases in Brazil sheds light on the genotype-phenotype correlation and helps the better understanding of the disease and the prediction of its clinical course, enabling the provision of a more refined genetic counseling to the affected families.
Asunto(s)
Mucopolisacaridosis II , Brasil , Genotipo , Humanos , Masculino , Mucopolisacaridosis II/genética , Mutación , FenotipoRESUMEN
In Hunter syndrome (mucopolysaccharidosis II [MPS-II]), systemic accumulation of glycosaminoglycans (GAGs) due to a deficiency of iduronate-2-sulfatase (IDS), caused by mutations in the IDS gene, leads to multiple somatic manifestations and in patients with the severe (neuronopathic) phenotype, also to central nervous system (CNS) involvement. These symptoms cannot be effectively treated with current enzyme-replacement therapies, as they are unable to cross the blood-brain barrier (BBB). Pabinafusp alfa, a novel IDS fused with an anti-human transferrin receptor antibody, was shown to penetrate the BBB and to address neurodegeneration in preclinical studies. Subsequent phase 1/2 and 2/3 clinical studies in Japan have shown marked reduction of GAG accumulation in the cerebrospinal fluid (CSF), along with favorable clinical responses. A 26-week, open-label, randomized, parallel-group phase 2 study was conducted in Brazil to further evaluate the safety and efficacy of intravenously administered pabinafusp alfa at 1.0, 2.0, and 4.0 mg/kg/week in MPS-II patients. The safety profiles in the three dosage groups were similar. Neurodevelopmental evaluation suggested positive neurocognitive signals despite a relatively short study period. The 2.0-mg/kg group, which demonstrated marked reductions in substrate concentrations in the CSF, serum, and urine, was considered to provide the best combination regarding safety and efficacy signals.
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Anticuerpos Monoclonales/administración & dosificación , Terapia de Reemplazo Enzimático/métodos , Iduronato Sulfatasa/administración & dosificación , Mucopolisacaridosis II/tratamiento farmacológico , Receptores de Transferrina/antagonistas & inhibidores , Proteínas Recombinantes de Fusión/administración & dosificación , Adolescente , Adulto , Brasil/epidemiología , Niño , Quimioterapia Combinada , Femenino , Humanos , Masculino , Mucopolisacaridosis II/epidemiología , Mucopolisacaridosis II/genética , Mucopolisacaridosis II/patología , Receptores de Transferrina/inmunología , Resultado del Tratamiento , Adulto JovenRESUMEN
BACKGROUND: Mucopolysaccharidosis type II (Hunter syndrome, or MPS II) is an X-linked lysosomal disorder caused by the deficiency of iduronate-2-sulfatase, which leads to the accumulation of glycosaminoglycans (GAGs) in a variety of tissues, resulting in a multisystemic disease that can also impair the central nervous system (CNS). OBJECTIVE: This review focuses on providing the latest information and expert opinion about the therapies available and under development for MPS II. METHODS: We have comprehensively revised the latest studies about hematopoietic stem cell transplantation (HSCT), enzyme replacement therapy (ERT - intravenous, intrathecal, intracerebroventricular, and intravenous with fusion proteins), small molecules, gene therapy/genome editing, and supportive management. RESULTS AND DISCUSSION: Intravenous ERT is a well-established specific therapy, which ameliorates the somatic features but not the CNS manifestations. Intrathecal or intracerebroventricular ERT and intravenous ERT with fusion proteins, presently under development, seem to be able to reduce the levels of GAGs in the CNS and have the potential of reducing the impact of the neurological burden of the disease. Gene therapy and/or genome editing have shown promising results in preclinical studies, bringing hope for a "one-time therapy" soon. Results with HSCT in MPS II are controversial, and small molecules could potentially address some disease manifestations. In addition to the specific therapeutic options, supportive care plays a major role in the management of these patients. CONCLUSION: At this time, the treatment of individuals with MPS II is mainly based on intravenous ERT, whereas HSCT can be a potential alternative in specific cases. In the coming years, several new therapy options that target the neurological phenotype of MPS II should be available.
Asunto(s)
Iduronato Sulfatasa , Mucopolisacaridosis II , Terapia de Reemplazo Enzimático , Glicosaminoglicanos/uso terapéutico , Humanos , Iduronato Sulfatasa/genética , Iduronato Sulfatasa/uso terapéutico , Mucopolisacaridosis II/tratamiento farmacológico , Mucopolisacaridosis II/genética , FenotipoRESUMEN
OBJECTIVES: To assess the outcome of population-based newborn screening for mucopolysaccharidosis type II (MPS II) during the first year of screening in Illinois. STUDY DESIGN: Tandem mass spectrometry was used to measure iduronate-2-sulfatase (I2S) activity in dried blood spot specimens obtained from 162 000 infant samples sent to the Newborn Screening Laboratory of the Illinois Department of Public Health in Chicago. RESULTS: One case of MPS II and 14 infants with pseudodeficiency for I2S were identified. CONCLUSIONS: Newborn screening for MPS II by measurement of I2S enzyme activity was successfully integrated into the statewide newborn screening program in Illinois.
Asunto(s)
Ácido Idurónico/análogos & derivados , Mucopolisacaridosis II/diagnóstico , Tamizaje Neonatal/métodos , Biomarcadores/sangre , Pruebas con Sangre Seca/métodos , Estudios de Seguimiento , Humanos , Ácido Idurónico/sangre , Illinois/epidemiología , Incidencia , Recién Nacido , Mucopolisacaridosis II/sangre , Mucopolisacaridosis II/epidemiología , Reproducibilidad de los Resultados , Estudios Retrospectivos , Espectrometría de Masas en Tándem/métodos , Factores de TiempoRESUMEN
RATIONALE: Mucopolysaccharidosis type II (Hunter syndrome) is an X-linked multisystem disorder, caused by deficiency of the lysosomal enzyme iduronate-2-sulfatase (I2S). The clinical manifestations of this disease are severe skeletal deformities, airway obstruction, cardiomyopathy, and neurologic deterioration. PATIENT: The patient was 5 years and 6 months boy, with developmental delay, hearing loss, hepatosplenomegaly, and skeletal dysplasia. He was diagnosed with mucopolysaccharidosis type II based on clinical manifestations, biochemical and genetic analysis. OUTCOMES: The patient carries a new mutation (c.879-1210_1007-218del) in hemizygosis in the IDS gene, which was defined as pathogenic according to the 2015 American College of Medical Genetics and Genomics-Association for Molecular Pathology guidelines and as responsible for the mucopolysaccharidosis type II phenotype in the patient.
RESUMEN
Hunter syndrome (Mucopolysaccharidosis II, MPS II) is an X-linked lysosomal storage disease produced by the deficiency of the lysosomal enzyme iduronate-2-sulfatase (IDS). Currently, MPS II patients are mainly treated with enzyme replacement therapy (ERT) using recombinant enzymes produced in mammalian cells. As an alternative, several studies have shown the production of active and therapeutic forms of lysosomal proteins in microorganisms. In this paper, we report the production and characterization of a recombinant IDS produced in the yeast Pichia pastoris (prIDS). We evaluated the effect of culture conditions and gene sequence optimization on prIDS production. The results showed that the highest production of prIDS was obtained at oxygen-limited conditions using a codon-optimized IDS cDNA. The purified enzyme showed a final activity of 12.45 nmol mg-1 H-1 and an apparent molecular mass of about 90 kDa. The highest stability was achieved at pH 6.0, and prIDS also showed high stability in human serum. Noteworthy, the enzyme was taken up by culture cells in a dose-dependent manner through mannose receptors, which allowed the delivery of the enzyme to the lysosome. In summary, these results show the potential of Pichia pastoris as a host to produce an IDS intended for a MPS II ERT.
Asunto(s)
Iduronato Sulfatasa/genética , Iduronato Sulfatasa/metabolismo , Lisosomas/enzimología , Pichia/genética , Animales , Biomasa , Reactores Biológicos , Western Blotting , Células CHO , Codón , Cricetulus , ADN Complementario/genética , Electroforesis en Gel de Poliacrilamida , Estabilidad de Enzimas , Fermentación , Células HEK293 , Semivida , Humanos , Concentración de Iones de Hidrógeno , Iduronato Sulfatasa/aislamiento & purificación , Oxígeno/metabolismo , Transporte de Proteínas , Proteínas Recombinantes/genética , Proteínas Recombinantes/aislamiento & purificación , Proteínas Recombinantes/metabolismo , TemperaturaRESUMEN
There is limited information regarding the long-term outcomes of hematopoietic stem cell transplantation (HSCT) for mucopolysaccharidosis II (MPS II). In this study, clinical, biochemical, and radiologic findings were assessed in patients who underwent HSCT and/or enzyme replacement therapy (ERT). Demographic data for 146 HSCT patients were collected from 27 new cases and 119 published cases and were compared with 51 ERT and 15 untreated cases. Glycosaminoglycan (GAG) levels were analyzed by liquid chromatography tandem mass spectrometry in blood samples from HSCT, ERT, and untreated patients as well as age-matched controls. Long-term magnetic resonance imaging (MRI) findings were investigated in 13 treated patients (6 ERT and 7 HSCT). Mean age at HSCT was 5.5 years (range, 2 to 21.4 years) in new patients and 5.5 years (range, 10 months to 19.8 years) in published cases. None of the 27 new patients died as a direct result of the HSCT procedure. Graft-versus-host disease occurred in 8 (9%) out of 85 published cases, and 9 (8%) patients died from transplantation-associated complications. Most HSCT patients showed greater improvement in somatic features, joint movements, and activity of daily living than the ERT patients. GAG levels in blood were significantly reduced by ERT and levels were even lower after HSCT. HSCT patients showed either improvement or no progression of abnormal findings in brain MRI while abnormal findings became more extensive after ERT. HSCT seems to be more effective than ERT for MPS II in a wide range of disease manifestations and could be considered as a treatment option for this condition.
Asunto(s)
Terapia de Reemplazo Enzimático/métodos , Trasplante de Células Madre Hematopoyéticas/métodos , Mucopolisacaridosis II/terapia , Adolescente , Niño , Preescolar , Glicosaminoglicanos/sangre , Enfermedad Injerto contra Huésped , Trasplante de Células Madre Hematopoyéticas/efectos adversos , Trasplante de Células Madre Hematopoyéticas/mortalidad , Humanos , Imagen por Resonancia Magnética , Adulto JovenRESUMEN
BACKGROUND: Mucopolysaccharidosis (MPS) type II is produced by a deficiency of iduronate-2-sulfatase (I2S). The quantification of the enzyme activity in leukocytes is used as diagnostic confirmation of MPS. OBJECTIVE: To determinate the cost-effectiveness of the measurement of I2S enzyme activity in leukocytes compared with not carrying out the enzyme activity measurement for diagnostic confirmation of MPS II from the perspective of the Colombian health system. METHODS: A cost-effectiveness analysis was conducted on the basis of a decision tree model. The measure of effectiveness was the correct diagnosis of cases of MPS II. The costs of I2S enzymatic quantification in leukocytes, consultation with a geneticist and with other specialists, and costs of diagnostic procedures were included. The time horizon was less than 1 year. A probabilistic sensitivity analysis was performed using Monte-Carlo simulation with 10,000 iterations. RESULTS: The incremental cost was -US $43,145 with an incremental effectiveness of 42 cases. The probabilistic sensitivity analysis confirms the results of basal data, in which the quantification of I2S enzyme activity was less costly and more effective than the alternative. CONCLUSIONS: The quantification of I2S enzymatic activity is a dominant technology for the diagnostic confirmation of MPS II, compared with not making the quantification, from the perspective of the Colombian health system.
Asunto(s)
Enzimas/análisis , Leucocitos/enzimología , Mucopolisacaridosis II/diagnóstico , Colombia , Análisis Costo-Beneficio , Terapia de Reemplazo Enzimático , Humanos , Iduronato Sulfatasa , América Latina , Mucopolisacaridosis II/enzimología , Mucopolisacaridosis IV , Mucopolisacaridosis VI , Enfermedades RarasRESUMEN
This review aims to provide clinicians in Latin America with the most current information on the clinical aspects, diagnosis, and management of Hunter syndrome, a serious and progressive disease for which specific treatment is available. Hunter syndrome is a genetic disorder where iduronate-2-sulfatase (I2S), an enzyme that degrades glycosaminoglycans, is absent or deficient. Clinical manifestations vary widely in severity and involve multiple organs and tissues. An attenuated and a severe phenotype are recognized depending on the degree of cognitive impairment. Early diagnosis is vital for disease management. Clinical signs common to children with Hunter syndrome include inguinal hernia, frequent ear and respiratory infections, facial dysmorphisms, macrocephaly, bone dysplasia, short stature, sleep apnea, and behavior problems. Diagnosis is based on screening urinary glycosaminoglycans and confirmation by measuring I2S activity and analyzing I2S gene mutations. Idursulfase (recombinant I2S) (Elaprase(®), Shire) enzyme replacement therapy (ERT), designed to address the underlying enzyme deficiency, is approved treatment and improves walking capacity and respiratory function, and reduces spleen and liver size and urinary glycosaminoglycan levels. Additional measures, responding to the multi-organ manifestations, such as abdominal/inguinal hernia repair, carpal tunnel surgery, and cardiac valve replacement, should also be considered. Investigational treatment options such as intrathecal ERT are active areas of research, and bone marrow transplantation is in clinical practice. Communication among care providers, social workers, patients and families is essential to inform and guide their decisions, establish realistic expectations, and assess patients' responses.
RESUMEN
In this study, 103 unrelated South-American patients with mucopolysaccharidosis type II (MPS II) were investigated aiming at the identification of iduronate-2-sulfatase (IDS) disease causing mutations and the possibility of some insights on the genotype-phenotype correlation The strategy used for genotyping involved the identification of the previously reported inversion/disruption of the IDS gene by PCR and screening for other mutations by PCR/SSCP. The exons with altered mobility on SSCP were sequenced, as well as all the exons of patients with no SSCP alteration. By using this strategy, we were able to find the pathogenic mutation in all patients. Alterations such as inversion/disruption and partial/total deletions of the IDS gene were found in 20/103 (19%) patients. Small insertions/deletions/indels (<22 bp) and point mutations were identified in 83/103 (88%) patients, including 30 novel mutations; except for a higher frequency of small duplications in relation to small deletions, the frequencies of major and minor alterations found in our sample are in accordance with those described in the literature.
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Exones , Iduronato Sulfatasa/genética , Mucopolisacaridosis II/genética , Mutación , Adulto , Femenino , Estudios de Asociación Genética , Técnicas de Genotipaje , Humanos , Mucopolisacaridosis II/diagnóstico , Mucopolisacaridosis II/patología , Análisis de Secuencia de ADN , Índice de Severidad de la Enfermedad , América del SurRESUMEN
Hunter disease or mucopolysaccharidosis type II (MPS II) is an X-linked recessive lysosomal disorder caused by the deficit of the enzyme iduronate-2-sulfatase (IDS), involved in the catabolism of the glycosaminoglycans heparan and dermatan sulfate. Our aim was to search for molecular defects in the promoter region of the IDS gene in patients with previous biochemical diagnosis of MPS II and after we sequenced the whole IDS coding region and the exon/intron boundaries without detecting any pathogenic mutations. Screening of the promoter region of four patients detected in two of them a 178 bp deletion and in the other two a single nucleotide substitution 818 bp upstream of the coding region. The latter had never been described before in MPS II patients and it turned out to be a polymorphism. Our experience suggests that MPS II patients with no mutations detected in the IDS coding region should be screened in the promoter region of the gene. Findings will hopefully help to clarify the relationship between genotype and phenotype and will be useful for the correct molecular diagnosis of Hunter patients and the identification of female carriers, the latter particularly important for genetic counseling.